Just over 100 sick refugees on Manus Island and Nauru have been approved for transfer to Australia since the so-called medevac laws were enacted against the government's wishes six months ago.

Hugh de Kretser, from the Human Rights Law Centre, says the laws put doctors at the heart of decisions about medical care and must not be repealed.

"Removing a fair, transparent and doctor-led process for accessing essential, and in many cases, life-saving medical care is cruel and unnecessary," he said on Monday.

"Repealing the medevac laws will increase the risk of more innocent people dying on Nauru and Manus."

The government is determined to scrap the medevac laws, with a Senate committee now tasked with examining its plans.

As the laws stand, Home Affairs Minister Peter Dutton can veto medical transfers on national security grounds but he has not yet done so.

Mr de Kretser told the committee 22 applications have been refused on medical grounds before being referred to an independent panel for review.

The panel has overruled the minister eight times to allow the transfers to proceed.

Mr Dutton argues "repairing" the legislation will ensure the government is able to determine who enters the country.

"As a nation it is imperative we are able to determine who enters Australia and whether they should remain in our borders permanently," he told parliament in last month.

Former federal MP Kerryn Phelps, who was a lead advocate for the medevac laws, said on Monday repealing the changes would put the transfer of sick refugees back in the hands of politicians and bureaucrats.

"We will return to the previous situation, when court orders and legal intervention were required to ensure critically sick people received the medical treatment they needed," Dr Phelps told the committee.

"Doctors will again fear further unnecessary deaths and a return to a slow, unpredictable and dangerous transfer system."